Insulated built up roof and insulation therefor



Aug- 16, 1956 J. N. cosBY ET AL INSULATED BUILT UP ROOF AND INSULATIGN THEREFOR Filed July I5, 1962 United States Patent O INSULATED BUILT UP ROOF AND INSULATION THEREFOR John N. Cosby and Richard K. Eberts, Morristown, NJ., assiguors to Allied Chemical Corporation, New York,

N.Y., a corporation of New York Filed July 3, 1962, Ser. No. 207,259 4 Claims. (Ci. 52-309) This invention relates to roof structure, and, more particularly, to roofs for homes, food markets, shopping centers and industrial buildings, many of which are air conditioned, and which roofs are provided with insulation to maintain the interior cooler during summer, With -less load on the air conditioning system in the case of air conditioned buildings, and to conserve heat during winter. This invention includes such roof structures as lwell as the novel insulating material employed to form the heat insulating layer or portion thereof.

Built up flat roofs, comprising several alternate layers or plies of waterproofed rooting felt and coal tar pitch or asphalt coating layers, a top layer of pitch, asphalt or other binder in which is partially embedded gravel, slag, markle chips or tile forming the exposed or traffic surface, and having a layer of insulation between the roof deck and the lowermost felt layer are known. Fiberboard, foamed polystyrene, glass fiber, perlite and cellular 4glass have been suggested and used as insulating materials.

All of these known insulating materials have relatively high thermal conductivities. Cellular glass is rigid and brittle and frequently breaks in lhandling and in use due to the irregularities often present on a roof deck. Foamed polystyrene has the disadvantage and drawback that the molten bitumen employed in bonding the overlying felt layer to the insulation melts and destroys or damages the foamed polystyrene. Moreover, when cut back adhesives, i.e., adhesives containing solvents which evaporate and thus cause the adhesive to set, are employed as the bond-ing media in forming the built up roof, the solvents attack and damage the polystyrene.

It is a principal object of the present invention to provide a roof structure having an insulating layer beneath the alternate layers of waterproofed rooting felt and waterproofing binder, which insulating layer is of markedly greater thermal eiciency than other known types of insulation, including the insulating materials hereinabove mentioned.

It is a further object of the present invention to provide a roof insulation member in the form of a board or unit of suitable size and thickness having a unique combination of properties which make it a superior roof insulation, namely: it has markedly greater thermal emciency; does not absorb Water; can be mopped with hot pitch or asphalt without deleterious effect on the insulation in the course of the construction of the built up roof; provides a walk-on, work-on surface over which a Workman can walk and transport in wheelbarrows, dump carts or other such equipment, necessary materials required in the construction of the roof, and on which can be placed buckets of waterproofing material, rolls of felt and other loads distributed over relatively small areas, all without crushing or forming deep impressions therein or destroying the insulating value of the insulation.

Still another object of this invention is to provide a roof having an insulating layer constituted of a plurality of board-.like units of suitable size for easy handling adapted to be laid in abutting relation to produce the insulating layer which is mechanically strong, chemically 3,266,206 Patented August 16, 1966 ice inert, resistant to heat, highly durable and practically impervious to Water.

Other objects and advantages of this invention will be apparent from the following description thereof, taken in connection with the accompanying drawings in which is shown, for purposes of exemplication, a preferred embodiment of `this invention without, however, limiting the claimed invention to this illustrative embodiment.

In the drawings,

FIGURE 1 is a fragmentary perspective of a vertical section showing the several layers, with portions broken away to show the interior structure, of a roof embodying the present invention; and

FIGURE 2 is a fragmentary vertical section through the novel roof insulation embodying this invention.

Referring to the drawings, 10 is the roof deck of a building, which deck may be of wood, poured gypsum or concrete, precast slabs or other structural decks, or, in `the case of some industrial buildings, a uted steel deck with the flutes spaced relatively close to each other, Say, a few inches apart. The deck 10 is a flat or nearly fiat, i.e., may be pitched slightly. Employing a fluted steel deck the upper edges of the flutes lie in substantially the same plane. The insulation layer 15 rests on these upper edges or on the deck 10. Insulation layer 15 has suicient structural strength not to be deformed or damaged by the loads to which it is subjected, both dur-ing the construction of the built up roof and in the iinished roof, notwithstanding that the insulating layer 15 is supported at spaced areas by the edges or ridges of the flutes forming the fluted steel deck.

In the embodiment of the invention shown in FIGURE l, the roof deck 10 is provided with a vapor barrier 11 consisting of a layer of bituminous saturated and coated roofing felt 12, suitably bonded to the deck 10 by a llayer of Waterprooiing material `13:, desirably asphalt or coal tar pitch. The vapor barrier thus produced completely covers the entire area of the roof deck. The Ipresent invention, however, is not coniined to structures having such vapor barriers, although a vapor barrier construction is preferred. If desired, `the roof insulation 15 can be applied directly to the roof deck 10 being bonded thereto by a layer of water proofing material such as pitch or asphalt, the same as layer 1-3, in which case the felt layer 12 is omitted.

The roof insulation unit 1'5 contains a rigid urethane `foam layer or core 16, from 1A inch to 8 inches thick, preferably inch to 2 inches thick, having at least 50% by volume and preferably atleast by volume closed cells, as up to 95% or more, a compressive strength of at least 10 pounds per square inch with no more than 5% by volume deflection, preferably at least about 20 pounds per square inch with no more than 5% deliection, a density of from 1.1 to 4, preferably 1.5 to 2.5 pounds per cubic foot, a flexural strength at least 20 pounds per square inch, preferably at least 40 pounds per square inch, for example, up to to 100 pounds per square inch, and a k value not exceeding abou-t 0.24, preferably about 0.13 B.t.u. per hr. per sq. ft. per inch thickness per F. The lc values in this speciiicaton indicate the thermal conductivity of the material, the lower the k value, the lower the thermal conductivity, i.e., the better the insulating value.

For rigid urethane foams in which the cells 9 are filled with chlorouoromethanes or chloroiiuoroethanes, preferably monoiiuorotrichloromethane, the k value is 0.13; for such foams in which the cells are lled with CO2, the k value is 0.24. A typical Core 16 may be one inch thick, have closed pore volume of at least compressive strength of 22 pounds per square inch with less than by volume deflection, density of about 1.8 pounds per cubic foot, flexural strength of 40 pounds per square inch, and a k value of about 0.13 B.t.u. per hr. per sq. ft. per inch thickness per F.

The back 17 of rigid urethane core 16 has bonded thereto a sheet of waterproofed felt which completely covers the back 17 with the edges of the felt coterminal with the edges of the back 17. The face or top surface 19 has bonded thereto a sheet 20 of waterproofed felt which completely covers face 19 with the edges of the felt coterminal with the edges of the face 19. Preferably each of the cap sheets 18 and 20 is roofing felt saturated with a bituminous ma-terial and coated on the opposite sides with bituminous coating material, desirably `asphalt or pitch. The top coating layer 19' thus produced on felt 18 can be employed to effect the bonding of the felt sheet 18 to the back 17. Similarly the coating layer 21 on the underside of the felt sheet 20 can be used to effect the bonding of this felt or cap sheet 20 to the face 19 of the core.

The surface of felt or cap sheet 20 has a layer of antistick material 22 in the coating layer 22 thereon. Coating layer 23 on felt 18 may be free of such anti-stick material, but preferably has anti-stick material applied thereto. The layer of anti-stick material 22 and the top coating layer 22 provide a protective wearing surface for the insulation layer during laying of the built up roof when workmen walk over the insulation layer 15, and this layer is subject to loads such as wheelbarrows, dump carts, etc., propelled thereover, or rolls of roofing felt. Preferably sheets 18 and 20 are each of roofing felt impregnated or saturated with a waterproofing material, such as asphalt or coal tar, and coated on t-he opposite sides thereof with a layer of waterproofing material, desirably bituminous material, such as asphalt or coal tar pitch.

The resulting sandwich-like unit or laminate is made of any desired dimension for easy handling, of rectangular shape so that the units can be laid in abutting relation. Typical size is 3 feet by 4 feet rectangular units having a total thickness of 1.1 inches, `the core 16 being 1 inch thick, and the coated sheets 18 and 20 each being lapproximately 0.05 inch thick.

To the top of insulating layer 15, i.e., to layer 22, is applied a coating of waterproofing material 24 such as hot asphalt or hot coal tar pitch having a softening point of Iabout 140 to 200 F. applied at a temperature of about 350 to 450 F. Instead of such hot application of the binder a cut-back adhesive containing a solvent can be applied at ambient temperatures to effect the bonding of the respective felt layers `to each other and the lowermost felt layer to the insulation 15. Coating 24 covers the entire area of the roof surface, including the joints J between abutting units of the insulating material. Applied to coating layer 24 are alternate layers of waterproof roofing felt 25 and waterproof coating layers 26, each covering the entire area of the roof. Usually 2 or 3 waterproof felt layers are applied with waterproof coating layers between adjacent felt layers bonding the lowermost felt layer to the insulating layer 15 and on top of the top felt layer. The invention, however, is not limited to roof constructions having 3 or 4 layers of rooting felt alternating with coating layers. It includes roofs employing only 2 layers of roofing felt, or more lthan 4 layers of such felt, each bonded by a waterproof coating layer with the underlying felt layers.

To the top coating layer 26 is applied a layer of slag or gravel 27 forming a wearing or traffic surface. Instead of such gravel surface, tile can be laid in the top coating layer 26 and bonded thereby to the underlying roof construction.

The rigid urethane foam of which the layer or core 16 is constituted can be produced by known procedures of reacting a polyfunctional organic isocyanate and a high molecular weight polyol or polyether. Two types of process are generally used `for producing such foams, namely, the one shot process and the so-called prepolymer method. In the one shot process, the diisocyanate, polyol or polyether are mixed simultaneously along with suitable catalysts, foam stabilizers, cell size control agents and blowing agent. In the prepolymer process, a portion of the polyol or polyether is mixed with the isocyanate to produce a prepolymer usually containing a large excess of unreacted isocyanate and 4the prepolymer thus formed reacted with the remainder of polyol or polyether in the presence of catalysts, foaming agents, stabilizers, cell size control agents, etc.

Isocyanates suitable for making such foams include, among many others, 2,4- and 2,6-tolylene diisocyanates, phenylene diisocyanate 3,3-bitolylene-4,4diisocyanate, methylene di-p-phenyleneisocyanate, 1,5-naphthalene diisocyanate, and a triisocyanate prepared by reacting 3 mols of tolylene diisocyanate with one mol of hexanetriol.

Polyols and polyethers suitable for making rigid foams `include (l) trihydric alcohols such as glycerin, castor oil, etc.; (2) polyalkylene ether glycols prepared from ethylene, propylene or tetramethylene glycols, including polybutylene glycol of molecular weight 3000, derived from 1,4-butylene glycol, known commercially as Teracol 30; (3) polyethers having hydroxyl numbers from 300 to 700, including polyethers derived from propylene oxide; and (4) polyesters which are the reaction products of dihydric alcohols and dicarboxylic acids, for example, polyesters prepared by copolymerizing a dicarboxylic acid, such as adipic, phthalic, sebacic, ysuccinic, or oxalic acid, with a glycol or polyalkylene glycol, such as ethylene, diethylene, propylene and butylene gly-cols, or obtained by copolymerizing ethylene glycol or glycerin with a mixture of phthalic and adipic acids; the last mentioned polyesters are alkyd resins.

Catalysts used can be the amines, such as dimethylethanolamine, tetrahydroxypropylethylenediamine and other amines, including tertiary amines, used as catalysts in the production of urethane foams, and tin compounds such as stannous octoate, dibutyltin dioctoate and dibutyltin dilaurate.

Foam stabilizers and ne cell forming agents are the silicones, such as those of the dimethyl siloxane type, or alkylsilanepolyoxyethylene copolymers.

Blowing agents can be water, which react with the isocyanate to liberate carbon dioxide to produce the foam, nitrogen, air, carbon dioxide or the chlorofluoromethanes or chlorouoroethanes; the latter blowing agents result in urethane foams of maximum insulation value. Particularly preferred is monotluorotrichloromethane. These chlorinated uorinated hydrocarbons result in low density urethanes having a maximum cell size of about 30 mils and typically averaging 10-15 mils, diameter and unusually low thermal conductivity. The cells 9 are shown on the drawing greatly enlarged lfor illustrative purposes.

In general, such rigid urethane foams are produced employing a formulation containing sufficient polyfunctional molecules to produce cross-linking with consequent production of closed cells 9 in amount of at least 50% of the total cells in the body, preferably at least and desirably up to or more. A tri-functional molecule, eg., glycerin, contributes 1 mol of cross links per mol equivalent, and a `tetra-functional molecule, 2 mols, and so on. Since the production of such rigid foams is known to those skilled in the urethane art, it is believed that further description of the production of such foams is unnecessary.

Bonding of the rigid urethane core 16 to the roofing sheets 18 and 20 can be effected by sandwiching a slab of rigid urethane foam of desired thickness betwen the sheets 18 and 20 coated at least on the side to be applied to the core while the coating layers 19 and 21 are still hot and plastic, and then subjecting the resultant assembly to pressure, for example by passage `between press rolls,

to effect bonding of the waterproofing sheets 1S and 20 to the slab of foam. Alternatively, a coating layer of hot asphalt or pitch or cut-back adhesive of a bituminous character can be applied to the surfaces of the rigid urethane foam slab, the waterproof sheets 18 and 20 applied, and the assembly subjected to pressure, to produce firm bonding of the waterproofing cap sheets to the slab of foam 16. rThe assembly thus produced, after cooling, is cut into units of the desired size, for example, three feet by four feet, or any other size that can be handled conveniently.

An important feature of this invention is that the opposite sides of the rigid urethane core or layer 16 have bonded thereto the waterproof cap sheets 18 and 20. These sheets protect the surfaces of the urethane slab. For example, sheet 20 provides a walk-on, work-on surface for the roofer, 4and a protective surface against damage to the underlying urethane core by the workmen walking thereon and from the temporary deposition of rolls of felt, buckets of asphalt, wheelbarrows, carts and other loads distributed over small areas employed in producing a built up roof. The sheets 18 and 20 of waterproofing material impart balance to the resultant structure. Rigid urethane panels having a sheet on one side only tend to Warp. The double sheet essentially eliminates expansion tendencies, the resultant product is substantially non-warping.

When urethane slabs provided with no facing sheet or with but a single upper sheet are laid on hot asphalt, the corners and edges of the panels warp or lift as much as an inch or more. Another serious problem `with foam panels not having the double facer sheets of the product embodying this invention arises when such panels becorne wet before or during application. Steam formed from moisture that may be present when the urethane foam is contacted with hot asphalt further increases the expansion of the foam. The product of this invention does not have these objectionable properties; the opposed sheets prevent contact of the rigid foam with the hot asphalt, protect the rigid foam against heat and water, and provide a balanced structure which remains fiat under all conditions normally encountered during handling and application.

The sheets 18 and 20 of waterproofed felt also provide protection from the standpoint that use of urethane foams without such covering layers can involve damage to the foam should the asphalt or other waterproof binder 'be applied at a higher than usual temperature. While the rigid urethane foams are not seriously damaged as a general rule by hot asphalt and in this respect are markedly superior to polystyrene foams, the application of asphalt at excessively high temperatures has a tendency to swell the foam. Using `the product of this invention, protection is provided because the cap sheets or covering sheets of waterproof roofing felt are not damaged by the application of asphalt or other waterproofing material, even though the temperature thereof should be unusually high.

The sheets 18 and 20 are substantially impervious to water and vapor, being made from felt which is saturated with a waterproofing material and coated with layers of waterproofing material, preferably asphalt or coal tar pitch. They prevent diffusion of gases and vapor into the cells of the urethane foam, and the loss of foaming agent, which, as indicated, is preferably chloroiiuoromethane or chlorofluoroethane, from the cells. Hence they maintain the high insulating value of the insulating layer 15.

The roof insulation of this invention involving a rigid urethane layer or core, having bonded thereto on the opposite sides thereof 'waterproofed felt layers, has at least twice the thermal eliiciency of other known types of roof insulation, does not absorb water, can be laid with hot pitch or asphalt without injury, and provides a walk-on, `work-on surface for the roofer. Its thermal conductivity is so low that it can be used whereever the roof insulation requirements are the most rigid, such as electrically heated, air conditioned, or cold storage buildings and struc-tures designed for optimum comfort. The preferred embodiment of this invention involving a rigid urethane foam in which the cells are filled with chlorofluoromethane or chlorofluoroethane, preferably monofluorotrichloromethane has a k value of 0.13 B.t.u. per hr. per sq. ft. per inch thickness per F. This cornpares with 0.27 for glass fiber and 0.30 for polystyrene, 0.34 for expanded perlite, 0.36 for iiberboard, and 0.40 for cellular glass. Thus, as compared with polystyrene, for example, more than twice the thickness of polystyrene must be used to obtain substantially the same heat insulation as provided by the heat insulating layer embodying this invention. In addition to this important advantage, the combination of rigid urethane core or layer 16 with the waterproof sheets 18 and 20 bonded thereto has the advantage that the insulating value remains stable because of the protection given to the core by the facer sheets; the panels, typically of 3 x 4 size, are easy to handle and install; the greater insulating value permits use of thinner panels when desired; the units are dimensionally stable and rigid, permitting tight butting of adjacent panels to form joints which minimize loss of hea-t; and the panels when installed can have applied thereto hot `pitch or asphalt which 4will not damage the heat insulation, or can have applied thereto cutback adhesives containing solvents without damage to the insulating layer.

Since different embodiments of the built up roof and the insulation therefor could be made `without departing from the scope of this invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A composite roof structure comprising a roof deck, a layer of insulation of substantially uniform thickness covering the deck, the insulation a plurality of relatively large, substantially rectangular units in edge abutting relation, each unit consisting of a rectangular core of rigid urethane foam of uniform composition throughout the core, containing at least 50% closed cells, having a thickness of from 1A, inch to 8 inches, a compressive strength of at least 10 pounds per square inch with no more than 5% deformation, a density of from 1.1 to 4 pounds per cubic foot, a flexural strength of at least 20 pounds per square inch, and a k value not exceeding 0.24 B.t.u. per hr. per sq. ft. per inch thickness per F. and a layer of felt saturated with a bituminous water-proofing material and coated with a bituminous water-proofing coating material factory bonded to each of the opposite surfaces of said urethane foam so that said units as laid each have the foam core protected by said felt covering the opposite sides thereof, at least one of said layers of felt having a layer of anti-stick material on the side opposite the urethane foam core, said roof structure having on said layer of insulating alternating layers of waterproof coating and bonding material and felt with the `top coating layer on the top felt layer having a wearresistant surface.

2. A composite roof structure as defined in claim 1, in which the core of rigid urethane foam contains at least 75% closed cells filled with chlorinated fluorinated hydrocarbons having from 1 to 2 carbon atoms, said core having a thickness of from 3%; inch to 2 inches, a density of from 1.5 to 2.5 pounds per cubic foot, a flexural strength of at least 20 pounds per square inch, and a k value of about 0.13 B.t.u. per hr. per sq. ft. per inch thickness per F.

3. Roof insulation comprising a relatively large, substantially rectangular unit adapted to be laid with other such units in edge abutting relation to form a layer of insulation of substantially uniform thickness, each unit consisting of a rectangular core of rigid urethane foam of uniform composition throughout, containing at least 50% closed cells, having a thickness of from 1A; inch to 8 inches, a compressive strength of at least 10 pounds per square inch with no more than 5% deformation, a density of from 1.1 to 4 pounds per cubic foot, a exural strength of at least 20 pounds per square inch, and a k value not exceeding 0,24 B.t.u. per hr. per sq. ft. per inch thickness per F., and a layer of felt saturated with a bituminous water-proofing material and coated with a bituminous vwater-proofing coating material factory bonded to each of the opposite surfaces of said urethane foam so that said units as laid each have the foam core protected by said felt covering the opposite sides thereof, at least one of said layers of felt having a layer of anti-stick material on the side opposite the urethane foam core.

4. The roof insulation as delined in claim 3, in which the board-like core of rigid urethane foam contains at least 75% closed cells filled with chlorinated fluorinated hydrocarbons having from 1 to 2 carbon atoms, said core having a thickness of from 3A inch to 2 inches, a density of from 1.5 to 2.5 pounds per cubic foot, a exural strength of at least 20 pounds per square inch, and a k Value of about 0.13 B.t.u. per hr. per sq. ft. per inch thickness per F.

References Cited by the Examiner UNITED STATES PATENTS 209,705 11/1878 Tobias 52-516 1,965,972 7/1934 Balph 52-516 2,962,183 11/1960 Rill et al. 3,029,172 4/1962 Glass 52-309 3,094,447 6/1963 Chamberlain 52-516 3,111,787 11/1963 Chamberlain 52-173 EARL I. WITMER, Primary Examiner. 

1. A COMPOSITE ROOF STRUCTURE COMPRISING A ROOF DECK, A LAYER OF INSULATION OF SUBSTANTIALLY UNIFORM THICKNESS COVERING THE DECK, THE INSULATION A PLURALITY OF RELATIVELY LARGE, SUBSTANTIALLY RECTANGULAR UNITS IN EDGE ABUTTING RELATION, EACH UNIT CONSISTING OF A RECTANGULAR CORE OF RIGID URETHANE FOAM OF UNIFORM COMPOSITION THROUGHOUT THE CORE, CONTAINING AT LEAST 50% CLOSED CELLS, HAVING A THICKNESS OF FROM 1/4 INCH TO 8 INCHES, A COMPRESSIVE STRENGHT OF AT LEAST 10 POUNDS PER SQUARE INCH WITH NO MORE THAN 5% DEFORMATION, A DENSITY OF FROM 1.1 TO 4 POUNDS PER CUBIC FOOT, A FLEXURAL STRENGTH OF AT LEAST 20 POUNDS PER SQUARE INCH AND A K VALUE NOT EXCEEDING 0.24 B.T.U. PER HR. PER SQ. FT. PER INCH THICKNESS PER *F., AND A LAYER OF FELT SATURATED WITH A BITUMINOUS WATER-PROOFING MATERIAL AND COACTED WITH A BITUMINOUS WATER-PROOFING COATING MATERIAL FACTORY BONDED TO EACH OF THE OPPOSITE SURFACES OF SAID URETHANE FOAM SO THAT SAID UNITS AS LAID EACH HAVE THE FOAM CORE PROTECTED BY SAID FELT COVERING THE OPPOSITE SIDES THEREOF, AT LEAST ONE OF SAID LAYERS OF FELT HAVING A LAYER OF ANTI-STICK MATERIAL ON THE SIDE OPPOSITE THE URETHANE FOAM CORE, SAID ROOF STRUCTURE HAVING ON SAID LAYER OF INSULATING ALTERNATING LAYERS OF WATERPROOF COATING AND BONDING MATERIAL AND FELT WITH THE TOP COATING LAYER ON THE TOP FELT LAYER HAVING A WEARRESISTANT SURFACE. 